The acrylate-styrene-acrylonitrile (ASA, terpolymer) resin has excellent processability, impact resistance and weatherability, as compared to butadiene-styrene-acrylonitrile (ABS) resin. Owing to its beneficial properties, it rapidly substitutes for paint-coated articles used for the outdoors and thus, be widely used in automotive parts, construction elements, sport supplies and the like. However, upon comparision with the conventional paint-coated articles, it still has shortcomings of deterioration in appearance properties such as scratch resistance, color stability, gloss and the like, causing deterioration of product quality.
As the most widely utilized method to improve appearance properties of the acrylate-styrene-acrylonitrile (ASA) resin, there has been proposed a method for blending the acrylate-styrene-acrylonitrile resin with a second resin which can supplement the weak properties of the acrylate-styrene-acrylonitrile. A representative example is a blend with methylmethacrylate (PMMA, Poly methyl methacrylate) resin. The methylmethacrylate resin has excellent weatherability, mechanical properties and surface scratch resistance and thus, is widely used in outdoor products. The compatibility of ASA (SAN) resin with the methylmethacrylate resin blend in the industrial aspect has been already reported in various literatures by Fower et al. (Polymer, 1987, vol 28, 1177 to 1184) and by Schafer et al. (Polymer, 1997, vol 38, 3745 to 3752). Also, acrylate-styrene-acrylonitrile/methylmethacrylate blend(ASA/PMMA) resin has been already commercialized. However, the blending method may affect adversely, such as reduction in gloss of the final blend product, when the molecular weight of the methylmethacrylate is wrongly selected, causing deterioration of appearance properties. Further, the product has poor impact strength at low temperature.
In addition, U.S. Pat. Nos. 6,476,126 and 4,579,909 disclose methods for producing a thermoplastic resin having excellent basic physical properties and appearance properties and weatherability, which comprises a 3-component blend of acrylate-styrene-acrylonitrile/methylmethacrylate/polycarbonate(ASA/PMMA/PC). The method has problems in that the resin has poor formability due to low flowability and also has poor economical efficiency, though it satisfies all the appearance properties as described above.